The present invention relates to water jet cutting machines and, more particularly, to such machines providing for separate delivery of a fluid under high pressure and an abrasive for mixing in the movable cutting head of a water jet cutting system.
Cutting of soft, elastic, heat sensitive materials as well as cutting of hard and brittle materials by use of a water jet containing an abrasive is a known process. Generally, the abrasive is mixed with the water jet within the cutting head and is delivered from a container which is moved with the cutting head. This container is capable of storing the required amount of abrasive for cutting of individual workpieces, and, usually, after each workpiece is cut, this storage container must be refilled or exchanged. Because the required supply of abrasives has to be moved in the storage container with the cutting head, the duration of the cutting process is limited, and the cutting speed is relatively slow due to the mass which has to be accelerated and moved.
The cutting fluid is put under very high pressure by means of a high pressure pump next to the cutting machine and is delivered through a high pressure line to the cutting head. Usually, the cutting head is guided on a movable carrier or on a robot arm. To accomplish this, an elbow-type high pressure tubing, which is freely supported, is generally used to connect the movable cutting head to the stationary pressure or pump amplifier through pipe-swivel fittings. It is also known to connect the high pressure tube through spiral-wound tube pieces which are located on the pressure amplifier and on the cutting head.
Based on this, German Patentschrift 3631116 describes the use of a spiral-wound tube between a gantry and the machine frame. From the end of the gantry, the high pressure tube is connected, and movable in a wide curve to the cutting head. Typically, high pressure lines are not protected and, therefore, are considerably endangered especially in situations where machines are loaded by cranes.
Accordingly, it is an object of the present invention to provide a novel water jet cutting machine in which a high pressure line and an abrasive feed line are carried from stationary sources to the cutting head by means of a pivoting connecting arm.
It is also an object to provide such a machine in which the supply of abrasive in a container at the cutting head is replenished automatically.
Another object is to provide such a machine which is relatively long lived and able to operate for relatively extended periods.